[Patent document 1] JP-2003-81059 A (US 2003/0046993 A1)
[Patent document 2] JP-2009-97272 A (US 2009/0102634 A1)
There is conventionally existing an apparatus that integrates a function of a keyless entry apparatus and a function of a tire pressure monitoring apparatus to each other by adopting a common component member such as a high frequency reception section that is used in common by the two functions. Such an integrating apparatus switches functions of the keyless entry apparatus and the tire pressure monitoring apparatus in conjunction with an ignition switch turning into ON and OFF states (see Patent document 1).
There is an area or nation such as the United States of America where installing of the tire pressure monitoring apparatus is compulsory. Such an area has a needs to primarily install the function as a tire pressure monitoring apparatus whereas eliminating the function as a keyless entry apparatus. Therefore, a system which integrates the function of the tire pressure monitoring apparatus and the function of the keyless entry apparatus is desirably configured to function as the tire pressure apparatus by easily separating the smart ECU for controlling smart entry. Thus, there is an apparatus in which the smart ECU may be easily separated (for example, refer to Patent document 2).
In contrast, there is an area or nation such as Japan where installing of the tire pressure monitoring apparatus is not compulsory, for example. Such an area has a needs to primarily install the function as a keyless entry apparatus whereas eliminating the function as a tire pressure monitoring apparatus.
In the apparatus described in above Patent document 2, a microcomputer for a tire pressure monitoring apparatus (TPMS microcomputer) is to switch the reception frequencies of the reception circuit depending on an ignition switch turning ON and OFF and the voltage of a voltage signal terminal RCO inputted from a smart ECU. Even if the integrating apparatus is intended to function only as a smart entry, the installing of the TPMS microcomputer is necessary, posing a problem.